US-12619035-B2 - Multiwavelength optical sources

Abstract

Configurations are disclosed for multi-wavelength optical devices and systems. In particular, multi-wavelength optical devices that include separate chips optically connected via phonic wire bonds. The disclosed configurations can utilize photonic wire bond interconnects and photonic wire bond interconnection techniques, which may facilitate low-cost implementation of wavelength division multiplexed optical systems.

Inventors

• Gordon Barbour Morrison
• Leif Albin Johansson

Assignees

• FREEDOM PHOTONICS LLC

Dates

Publication Date

20260505

Application Date

20220901

Claims (18)

1. 1 . An optical device comprising: a multi-wavelength optical source comprising: a plurality of optically active waveguides configured to provide optical gain having a plurality of output ports configured to output laser light amplified by the plurality of optically active waveguides; a photonic integrated circuit (PIC) comprising a plurality of input ports, and a plurality of narrow band optical reflectors configured to reflect at least a portion of light received from the plurality of input ports, and at least one PIC output port configured to output multi-wavelength light comprising laser light having at least two different wavelengths, wherein the PIC further comprises an optical multiplexer optically coupled to the plurality of narrowband optical reflectors and the at least one PIC output port, the optical multiplexer configured to combine light from the plurality of laser sources to form the multi-wavelength light; and a plurality of polymer waveguides connected to the plurality of input ports of the PIC and the plurality of output ports of the plurality of optically active waveguides, the plurality of the polymer waveguides configured to optically connect the plurality of output ports of the plurality of optically active waveguides to the plurality of input ports to form a plurality of laser sources comprising the plurality of optically active waveguides and respective narrowband optical reflectors, wherein the plurality of optically active waveguides and the PIC are fabricated on at least two separate substrates, wherein the plurality of polymer waveguides comprise polymer cladded polymer waveguides, and wherein the at least one PIC output port comprises a first PIC output port configured to provide a first multi-wavelength output and a second PIC output port configured to provide a second multi-wavelength output.
2. 2 . The optical device of claim 1 , wherein at least one of the polymer waveguides has a length and a cross-section orthogonal to the length that is round, circular, elliptically-shaped, or oval-shaped.
3. 3 . The optical device of claim 1 , wherein a polymer waveguide of the plurality of polymer waveguides is embedded in a polymer layer having an optical refractive index less than that of the polymer waveguide.
4. 4 . The optical device of claim 1 , wherein the laser light generated by the at least one PIC output port comprises a narrowband light output centered around a single center wavelength.
5. 5 . The optical device of claim 1 , further comprising a spot-size converter configured to convert a spot-size of light output by at least one optically active waveguide.
6. 6 . The optical device of claim 1 , wherein an optically active waveguide of the plurality optically active waveguides comprises a semiconductor optical amplifier configured to amplify the laser light.
7. 7 . The optical device of claim 1 , wherein the plurality of optically active waveguides comprise a plurality of back reflectors and a plurality of laser cavities are formed between the plurality of back reflectors and a plurality of the narrowband optical reflectors via the plurality of polymer waveguides.
8. 8 . The optical device of claim 7 , wherein the plurality of back reflectors comprise a highly reflective coating or a high reflectivity mirror at a back end of at least one of the plurality of optically active waveguides.
9. 9 . The optical device of claim 1 , wherein the PIC further comprises an optical multiplexer configured to receive light from the plurality of narrowband optical reflectors and provide the multi-wavelength light to the at least one PIC output port.
10. 10 . The optical device of claim 1 , wherein the PIC further comprises an optical multiplexer configured to combine light received from the plurality of the input ports and provide the multi-wavelength light to the at least one PIC output port.
11. 11 . The optical device of claim 10 , wherein the optical multiplexer comprises an arrayed waveguide grating (AWG).
12. 12 . The optical device of claim 1 , wherein at least one of the narrowband optical reflectors comprises a sampled grating Bragg reflector, a Bragg reflector, or a ring resonator.
13. 13 . The optical device of claim 1 , wherein the plurality of optically active waveguides are monolithically fabricated on a first chip of at least two separate chips, the first chip comprising IIIV semiconductor material.
14. 14 . The optical device of claim 13 , wherein the PIC comprises a planar light wave circuit (PLC) fabricated on a second chip of the at least two separate chips, the second chip comprising silicon.
15. 15 . The optical device of claim 1 , wherein the plurality of optically active waveguides are monolithically fabricated on a gain bar.
16. 16 . The optical device of claim 1 , wherein the plurality of optically active waveguides comprises a plurality of gain chips mounted on a carrier chip.
17. 17 . The optical device of claim 1 , wherein at least one narrowband reflector of the plurality of narrowband optical reflectors comprises a center wavelength different from the center wavelength of other narrowband reflectors.
18. 18 . The optical device of claim 1 , wherein a diameter of at least one of the polymer waveguides of the plurality of polymer waveguides does not exceed 20 microns along a length of the at least one of the polymer waveguides, or wherein a longitudinal distance between one of said output ports of a laser array and one of said input ports optically connected thereto via the polymer waveguides is less than 500 microns, or wherein a spacing between adjacent output ports of the plurality of output ports or a spacing between adjacent input ports of the plurality of input ports is less than 20 microns.

Description

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS This application claims benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63/240,851, entitled “MULTIWAVELENGTH OPTICAL SOURCES”, filed on Sep. 3, 2021, which is hereby incorporated herein by reference in its entirety. BACKGROUND Field of the Invention Various embodiments of this application relate to the integrated multi-wavelength optical devices and systems, and in particular, multi-wavelength sources based on heterogeneously integrated laser arrays and photonic integrated circuits. Description of the Related Art In optical telecommunication applications, multi-wavelength sources are routinely used to implement wavelength division multiplexing. Typically, the laser arrays that generate multi-wavelength light and optical devices that process the multi-wavelength light are fabricated on separate chips having different material compositions. Low loss optical power transfer between a laser array and the receiving optical devices fabricated on separate chips is important for supporting high quality data transfer. SUMMARY Multi-wavelength optical devices designs described herein can utilize photonic wire bond interconnects and photonic wire bond interconnection techniques, which may facilitate low-cost implementation of wavelength division multiplexed optical communication systems. Photonic wire bonds and bonding can be effective to provide low loss optical coupling between optical devices without the need for precise alignments between the corresponding optical ports. As discussed herein, photonic wire bonds may provide flexibility and other possible advantages. A variety of optical devices are disclosed herein. Some such optical devices comprise multi wavelength optical sources that comprise laser bars and arrays and photonic wire bonds wherein the laser bars and arrays are photonically wire bonded to photonic integrated circuits. Example embodiments described herein have several features, no single one of which is indispensable or solely responsible for their desirable attributes. Without limiting the scope of the claims, some of the advantageous features will now be summarized. BRIEF DESCRIPTION OF THE DRAWINGS In the following description of the various embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration various embodiments of the device. It is to be understood that other embodiments may be utilized and structural changes may be made. FIG. 1A illustrates an example multi-wavelength optical source configured to generate optical outputs having multiple wavelengths in accordance with certain embodiments described herein. The multi-wavelength optical source comprises a plurality of light sources (e.g., lasers) optically coupled to a wavelength multiplexer. FIG. 1B schematically illustrates a side cross-sectional view of an optical device (e.g., a multi-wavelength optical source) comprising a photonic integrated circuit (PIC) connected to a plurality of optical sources (e.g., lasers) via a plurality of air-cladded polymer waveguides. FIG. 1C schematically illustrates a side cross-sectional view of an example optical device (e.g., a multi-wavelength optical source) comprising a PIC optically connected to a plurality of optical sources via a plurality of encapsulated polymer waveguides. FIG. 1D schematically illustrates a side cross-sectional view of another example optical device (e.g., a multi-wavelength optical source) comprising a PIC optically connected to a plurality of optical sources via a plurality of air-cladded polymer waveguides. As illustrated, the air-cladded polymer waveguide is thicker in the middle in comparison to the ends where the thickness is reduced. FIG. 2 illustrates an example multi-wavelength source comprising a star coupler. FIG. 3 illustrates another example of a multi wavelength source comprising an arrayed waveguide grating (AWG). FIG. 4A illustrates an example of a laser chip comprising a semiconductor laser and an optical amplifier, mounted on a laser carrier chip. FIG. 4B illustrates schematically illustrates a laser array comprising a plurality of laser chips (e.g., similar to the laser chip shown in FIG. 4A) disposed on a laser carrier chip. FIG. 5 schematically illustrates the alignment between an output port of an optical source and an input port of a PIC. FIG. 6 illustrates an example of an optical system 600 comprising a plurality of lasers coupled to a PIC that includes an optical multiplexer and one or more optical devices and/or sub-systems receiving light from the optical multiplexer. FIG. 7 illustrates an example of an optical device comprising a plurality of dual output optical sources optically connected to two PICs. FIG. 8 illustrates an example of the optical device shown in FIG. 7 where each PIC comprises a star coupler. FIG. 9 illustrates an example of the optical device shown in FIG. 7 where each PIC comprises